On Thu, Jul 04, 2013 at 10:45:40AM +0200, Sebastian Hesselbarth wrote: > On 07/04/13 10:33, Sascha Hauer wrote: > > > >A componentized device never completes and it doesn't have to. A > >componentized device can start once there is a path from an input > >(crtc, i2s unit) to an output (connector, speaker). > > > >Consider what happens with a supernode approach. Your board provides a > >devicetree which has a supernode with hdmi and lvds referenced. Now you > >build a kernel with the hdmi driver disabled. You would still expect the > >lvds port to be working without having the kernel wait for the supernode > >being complete. > > > >Without supernode you can just start once you have everything between > >the crtc and lvds nodes. If later a hdmi device joins in then you can > >either notify the users (provided the DRM/KMS API supports it) or just > >ignore it until the DRM device gets reopened. > > Sascha, > > that is what it is all about. You assume you a priori know what devices > will be required for the componentized device to successfully output > a video stream. > > We have shown setups where you don't know what is required. Cubox > _needs_ lcd0 and hdmi-transmitter, Then your Cubox devicetree has a link (that's how they call it in v4l2, a link doesn't necessarily is a direct connection but can have multiple devices in it) between lcd0 and hdmi. > olpc just needs lcd0 and has built-in hdmi in the SoC (IIRC). And olpc has a link with lcd0 as the source and the builtin hdmi. > The driver needs to know what to wait for, and that is given by the DT super-node. You need a source (described in the devicetree), a sink (also described in the devicetree) and a link between them, nothing more. > > I consider kernels with missing drivers compared to what is given in > the DT as broken setup. What if your devicetree describes components not yet in mainline. Would you consider mainline kernels broken then? Sascha -- Pengutronix e.K. | | Industrial Linux Solutions | http://www.pengutronix.de/ | Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
